JP2008247960A - Light-shielding adhesive tape and lcd module produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-shielding adhesive tape resistant to the peeling between the light-shielding layer and the adhesive layer by repulsive force even under a high-temperature condition or a thermal cycling condition without using a halogen-containing vinyl chloride acetate resin. <P>SOLUTION: The light-shielding adhesive tape resistant to the peeling of the adhesive agent from an ink layer by repulsive force even under a high-temperature condition or a thermal cycling condition is a laminate of a resin film 1, a light-shielding layer 2 and an adhesive layer 4, wherein the light-shielding layer is placed between the resin film and the adhesive layer. The halogen-content of the light-shielding layer is ≤0.3 mass%, the light-shielding layer is a layer composed of an ink, the ink has an elastic modulus of 0.3-5 GPa in the form of a sheet having a thickness of 40 μm, and the tensile elongation of the ink is 0.5-10% under a tensile stress of 10 MPa. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-blocking pressure-sensitive adhesive tape, and more particularly to a light-blocking pressure-sensitive adhesive tape used by being attached between an LCD (Liquid Crystal Display) panel and a backlight housing.

  Display elements such as LCD modules (liquid crystal display devices) are used in a wide range of fields such as word processors and personal computers. Especially in electronic notebooks, mobile phones, PHS, etc. It has come to be used as a display device. Among such display elements, for example, a sidelight type backlight type LCD module (schematically shown in FIG. 5) generally includes a reflector 13, a light guide plate 12, a diffusion sheet in a backlight housing 14. 10. Prism sheet 9 (increased brightness) used as necessary and LCD panel 15 are laminated in order, LED (Light Emitting Diode) provided with a lamp reflector on the side of the light guide plate, cold cathode tube A light source 11 such as is arranged.

  Furthermore, an adhesive tape 8 (usually punched into a frame shape, and its width is usually about 0.5 mm to about 10 mm) is sandwiched between the LCD panel 15 and the backlight housing 14. The adhesive tape 8 is in contact with not only the backlight housing 14 but also the prism sheet 9, and serves to fix the diffusion sheet 10 and the like installed on the lower side of the prism sheet 9. It also has a role to prevent cracking of the above parts due to impact.

  In recent years, due to environmental considerations, it has been desired that peripheral materials for display devices such as LCD modules be shifted to VOC-free materials and halogen-free materials, and adhesive tapes used for display devices such as LCD modules are also used. It is not an exception. As a conventional pressure-sensitive adhesive tape, a pressure-sensitive adhesive tape having an ink layer in a light-shielding light-shielding layer is disclosed (for example, see Patent Documents 1 and 2). However, in these adhesive tapes, since an ink layer using a vinyl chloride resin as a binder resin is used for the light shielding layer, the ink layer does not use the vinyl chloride (hydrochloric acid / vinyl acetate) resin. Conversion was necessary.

  However, even if an ink using polyester resin or polyurethane resin other than PVC resin is applied as a light-shielding layer for light-shielding adhesive tape, there is a problem that the adhesive peels off from the ink due to the repulsive force of parts at high temperatures. Was.

JP 2004-156015 A JP 2004-184443 A

  An object of the present invention is to provide a light-shielding pressure-sensitive adhesive tape that does not easily cause peeling between the light-shielding layer and the pressure-sensitive adhesive layer due to repulsive force without using a vinyl chloride-based resin containing halogen. Is to provide.

  As a result of intensive studies, the present inventors have found that the light shielding layer provided on the resin film is an ink layer having a specific elastic modulus and tensile strength, thereby suppressing the flow of the ink layer and achieving the object of the present invention. I found it. That is, the present invention is a light-shielding pressure-sensitive adhesive tape having at least a resin film, a light-shielding layer and a pressure-sensitive adhesive layer, and having a light-shielding layer between the resin film and the pressure-sensitive adhesive layer, wherein the halogen content in the light-shielding layer Is 0.3% by mass or less, and the light-shielding layer is a layer made of colored ink. The elastic modulus of the ink in the form of a sheet having a thickness of 40 μm is 0.3 to 5 GPa, and the tensile strength is 10 MPa. It provides a light-shielding pressure-sensitive adhesive tape having an elongation percentage in the tensile direction of 0.5 to 10%.

  In the pressure-sensitive adhesive tape of the present invention, since the light-shielding layer provided on the resin film is an ink layer having a specific elastic modulus and tensile strength, the halogen content is low, and the repulsive force even under high-temperature conditions and cold cycle conditions. It was found that the pressure-sensitive adhesive did not peel off from the ink layer due to the above, and the above problems were solved.

  The light-shielding pressure-sensitive adhesive tape of the present invention having such characteristics can be suitably used for various display device applications, particularly for miniaturized LCD module applications that require light-shielding properties.

  The light-shielding pressure-sensitive adhesive tape of the present invention is a light-shielding pressure-sensitive adhesive tape having a light-shielding layer between a resin film and an adhesive layer, wherein the light-shielding layer has a halogen content of 0.3% by mass or less. The light-shielding layer is a layer made of colored ink, and the elastic modulus of the ink in the form of a sheet having a thickness of 40 μm is 0.3 to 5 GPa, and the elongation in the tensile direction at a tensile strength of 10 MPa. The rate is 0.5 to 10%.

[Resin film]
As the resin film used in the present invention, known and commonly used resin films used for pressure-sensitive adhesive sheets can be used, and examples thereof include cellophane, polyethylene, polypropylene, nylon, polystyrene, polyimide, and polyester. Among these, polyester is preferably used because it is excellent in strength and insulation.

  In the present invention, it is preferable that the resin film is a light-reflective resin film having light reflectivity because the luminance of a display device such as an LCD module can be increased. Of these, white polyethylene terephthalate having insulating properties and light diffuse reflection properties is most preferred. Moreover, when the resin film is a light-shielding resin film having a light-shielding property, it is preferable for increasing the contrast of the LCD when the LCD is used as a display device. Among them, black polyethylene terephthalate is preferable because it can provide excellent light shielding properties.

  Commercially available light-reflective resin films include Reiko 37W01, 3M ESR, Toray E20 # 38, Mitsubishi Chemical Polyester Film W400 # 38, Teijin DuPont Teflex FW2 # 13, etc. However, it is preferable because the thickness is thin and the reflectivity is high.

  As thickness of the resin film used as a support body, 6-100 micrometers is preferable. When the thickness is 6 μm or more, the film is hardly cracked at the time of peeling, and when it is 100 μm or less, peeling is hardly generated at the time of applying the phase. More preferably, it is 12-50 micrometers.

  Moreover, it is preferable to add various pigments, such as a white pigment and a black pigment, in a resin film, in order to provide reflectivity and light-shielding property. Various known additives such as an antioxidant and an antistatic agent may be added to the film.

[Adhesive layer]
The loss tangent of the dynamic viscoelastic spectrum at a frequency of 1 Hz of the pressure-sensitive adhesive layer used in the pressure-sensitive adhesive tape of the present invention is 0.35 to 0.70 at 85 ° C. Preferably it is 0.45-0.65. If it is less than 0.35, the pressure-sensitive adhesive becomes too hard and the initial adhesiveness is lowered. On the other hand, when it exceeds 0.70, the pressure-sensitive adhesive becomes too soft, and the pressure-sensitive adhesive stretches at high temperatures and peeling easily occurs.

  The dynamic viscoelasticity of the pressure-sensitive adhesive layer in the present invention is obtained by sandwiching a test piece between parallel disks, which are measuring parts of the tester, using a viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD). Then, the storage elastic modulus (G ′) and the loss elastic modulus (G ″) at a frequency of 1 Hz are measured, and the loss tangent is calculated by an expression represented by tan δ = (G ″) / (G ′). In the test piece, an adhesive having a thickness of 0.5 to 2.5 mm may be sandwiched between parallel disks alone, or a laminate of a base material and an adhesive may be stacked in layers and sandwiched between parallel disks. In the latter case, the thickness of the pressure-sensitive adhesive alone is adjusted to be in the above range. When the thickness of the pressure-sensitive adhesive is adjusted to the above range, the dynamic viscoelastic spectrum of the pressure-sensitive adhesive can be measured in the same manner as when there is no base material even if the base material is sandwiched between them.

  In addition, the pressure-sensitive adhesive layer can be a resin film or a light-shielding layer and has good adhesiveness, and known acrylic, rubber-based, and silicon-based pressure-sensitive resins can be used. Among them, an acrylic copolymer containing a repeating unit derived from an acrylate ester having an alkyl group having 2 to 14 carbon atoms as a repeating unit is preferable from the viewpoint of light resistance and heat resistance.

  Examples of the acrylic copolymer include acrylic copolymers containing repeating units derived from n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, ethyl acrylate, and the like. Among these, those having a halogen content of 0.3% by mass or less are preferable, those having a halogen content of 0.1% by mass or less are more preferable, and those having substantially no halogen are particularly preferable. Among them, those containing 50% by mass or more of n-butyl acrylate are excellent in adhesion to an ink layer using a polyurethane-based resin, more preferably those containing 90% by mass or more are excellent in adhesion.

  Furthermore, as a repeating unit, the repeating unit derived from an acrylic ester having a polar group such as a hydroxyl group, a carboxyl group or an amino group in the side chain or other vinyl monomer is contained in the range of 01 to 15% by mass. preferable. Moreover, it is excellent in adhesiveness with the ink layer which uses a polyurethane resin to contain an acrylic acid unit in 2-10 mass%.

  The acrylic copolymer can be obtained by copolymerization by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, an ultraviolet irradiation method, or an electron beam irradiation method. The average mass molecular weight of the acrylic copolymer is preferably 400,000 to 1,400,000, and more preferably 600,000 to 1,200,000.

  Furthermore, it is preferable to add a crosslinking agent in order to increase the cohesive strength of the pressure-sensitive adhesive. Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, and a chelate crosslinking agent. In particular, when an adhesive layer is provided, it is preferable to use an isocyanate crosslinking agent or an epoxy crosslinking agent. The addition amount of the crosslinking agent is preferably adjusted so that the gel fraction of the pressure-sensitive adhesive layer is 25 to 80%. A more preferable gel fraction is 30 to 70%. Among these, 35 to 60% is most preferable. When the gel fraction is 25% or more, adhesive residue hardly occurs when reworking. On the other hand, if the gel fraction is less than 80%, the adhesive strength is good. Adhesiveness decreases. The gel fraction is expressed as a percentage of the original mass by immersing the composition of the pressure-sensitive adhesive layer after curing in toluene, measuring the mass after drying of the insoluble matter remaining after standing for 24 hours, and measuring the mass.

  Furthermore, in order to improve the adhesive strength of the pressure-sensitive adhesive layer, a tackifier resin may be added. The tackifier resin to be added to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is a rosin resin such as rosin or an esterified product of rosin; a terpene resin such as a diterpene polymer or an α-pinene-phenol copolymer; Petroleum resins such as (C5) and aromatic (C9); styrene resins, phenol resins, xylene resins, and the like. An acrylic resin other than the acrylic copolymer may be added as a tackifying resin.

  As addition amount of tackifying resin, when an adhesive resin is an acrylic copolymer, it is preferable to add 10-60 mass parts with respect to 100 mass parts of acrylic copolymers. When attaching importance to adhesiveness, it is most preferable to add 20 to 50 parts by mass. When the adhesive resin is a rubber-based resin, it is preferable to add 80 to 150 parts by mass of the tackifier resin to 100 parts by mass of the rubber-based resin. In general, when the adhesive resin is a silicon resin, no tackifying resin is added.

  Moreover, black colorants, such as carbon black, and other well-known usual additives can be added as needed. Examples of other additives include plasticizers, softeners, fillers, pigments, flame retardants, and the like.

  As for the thickness of an adhesive layer, 5-50 micrometers is preferable, More preferably, it is 10-30 micrometers. If it is 5 μm or more, sufficient adhesiveness can be obtained, and if it is 50 μm or less, it can be suitably applied to a display device and the like that are becoming lighter and thinner.

[Shading layer]
The light shielding layer in the light-shielding pressure-sensitive adhesive tape of the present invention is a layer made of colored ink, and is a layer that suppresses the incidence of light by itself or by lamination with a resin film.

(Halogen content)
The light shielding layer in the light shielding adhesive tape of the present invention has a halogen content in the light shielding layer of 0.3% by mass or less. The content is preferably 0.05% by mass or less, and particularly preferably contains substantially no halogen. Here, the halogen content is a detection amount when analyzed by fluorescent X-rays. For example, as a fluorescent X-ray analyzer, “ZSX Primus”, “ZSX Primus II”, etc. manufactured by Rigaku are listed.

(Elastic modulus)
The ink used for the light shielding layer is an ink having an elastic modulus of 0.3 GPa to 5 GPa when a sheet-like sample having a thickness of 40 μm is formed using the ink. Preferably it is 0.4 GPa-5GPa, More preferably, it is 0.5 GPa-5GPa. If it is less than 0.3 GPa, the ink flows at a high temperature, and peeling occurs at the interface between the ink and the adhesive. At 5 GPa, the ink becomes too hard, the ink becomes brittle, and the ink tends to fall off the resin film when peeled off at high speed. The elastic modulus of the sheet sample is a value measured at 23 ° C. and a tensile speed of 300 / min.

(Elongation at 10MPa tensile strength)
The ink used for the light shielding layer is an ink in which the elongation in the tensile direction at a tensile strength of 10 MPa of a sheet-like sample having a thickness of 40 μm is 0.5 to 10%. Preferably it is 0.5 to 5%, more preferably 0.5 to 3%. If it is less than 0.5%, the ink becomes too hard, the ink becomes brittle, and the ink tends to fall off from the resin film when peeled off at high speed. If it exceeds 10%, the ink flows and peeling occurs at the interface between the ink and the pressure-sensitive adhesive. The elastic modulus of the sheet sample is a value measured at 23 ° C. and a tensile speed of 300 / min.

(Tensile strength at break)
In addition, the ink used for the light shielding layer preferably has a tensile strength at break of 20 to 50 MPa for a sheet-like sample having a thickness of 40 μm. More preferably, it is 21MPa-30MPa. The elastic modulus of the sheet sample is a value measured at 23 ° C. and a tensile speed of 300 / min.

(Tensile elongation at break)
The ink used for the light shielding layer preferably has a tensile elongation at break of 10 to 60% of a sheet sample having a thickness of 40 μm. More preferably, it is 20 to 50%. The elastic modulus of the sheet sample is a value measured at 23 ° C. and a tensile speed of 300 / min.

(Storage modulus E ')
The ink used for the light shielding layer is preferably a sheet-like sample having a thickness of 40 μm and having a storage elastic modulus E ′ of 0.1 to 1 GPa at 85 ° C. of the ink. More preferably, it is 0.15-0.8 GPa.

(Ink composition)
Although it does not specifically limit as a composition of the binder resin of the ink used for a light shielding layer, For example, a polyester-type resin, a polyurethane-type resin, and a polyamide-type resin are mentioned. Of these, polyurethane-based resins are most preferred for controlling the above elastic modulus.

  The polyurethane-based resin is obtained by a condensation polymerization reaction of a diisocyanate compound, a polyol compound, a low molecular weight chain extender, and the like, and a resin having a high flexibility and elasticity having many urethane bonds in the molecule is preferable. As a polyurethane-type resin used for this invention, the thing of mass average molecular weight 1,000-500,000 is preferable, More preferably, it is 30,000-100,000.

  Specific examples of the diisocyanate compound suitably used in the present invention include, for example, methylene diisocyanate, isopropylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and dimer acid. A chain aliphatic diisocyanate such as dimerisocyanate in which a carboxyl group is substituted with an isocyanate group; cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-di (isocyanatomethyl) cyclohexane, Cycloaliphatic diisocyanates such as methylcyclohexane diisocyanate; Dials such as 4,4′-diphenyldimethylmethane diisocyanate Dialkylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate such as 4,4'-diphenyltetramethylmethane diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4 Examples include aromatic diisocyanates such as' -dibenzyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and m-tetramethylxylylene diisocyanate; amino acid diisocyanates such as lysine diisocyanate. It is done. These polyisocyanate compounds including these diisocyanate compounds are used alone or in admixture of two or more.

  As the polyol compound suitably used in the present invention, for example, polyether polyols, polyester polyols, polycarbonate polyols, polybutadiene polyols and the like can be used. Examples of polyether polyols include polyethylene glycol obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran and the like, polypropylene glycol, polyoxytetramethylene ether glycol and the like. Examples of polyester polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, Saturated or unsaturated low molecular weight glycols such as 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol, bisphenol A and hydrogenated bisphenol A And dibasic acids such as adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, etc. Acid anhydrides corresponding to Water condensation compound obtained, and the like.

  In addition, it is preferable to add a cellulose-based resin having high dispersibility as a dispersant because high light-shielding properties can be obtained. Examples of the cellulose resin include nitrified cotton and cellulose acetate propionate. The addition amount of the resin is preferably 0.05 to 10% by mass with respect to the solid content of the ink. More preferably, it is 0.1-3 mass%.

  In addition, as the coloring material, a well-known and commonly used pigment or dye containing no halogen can be used. Carbon black in the case of black, titanium oxide, calcium carbonate, barium sulfate in the case of white, yellow oxidation in the case of yellow Iron or red is preferable from the viewpoint of batter, blue is cyanine blue, silver is aluminum powder, and pearl is mica titanium powder from the viewpoint of weather resistance, heat resistance, and dispersibility in the ink resin. Especially, what can form a black ink layer is preferable, and since carbon black has favorable light-shielding property, it is preferable.

  What is necessary is just to adjust suitably as addition amount of a coloring material according to a use etc., and 10 to 70% is preferable with respect to ink solid content. More preferably, it is 40 to 50%. If it is 10% or more, it preferably shows light shielding properties, and if it is 70% or less, the dispersion is good.

  Ink which comprises a light shielding layer can suppress generation | occurrence | production of the pinhole by blocking by containing an antiblocking agent. Anti-blocking agents include particle-based anti-blocking agents such as silica, calcium carbonate, calcium phosphate, and talc, and organic compound-based anti-blocking agents such as polyethylene wax (PE wax), fatty acid amide, fatty acid ester, and higher fatty acid. Is preferred. The particle-based anti-blocking agent prevents the blocking by forming irregularities on the surface of the ink layer and reducing the contact area between the ink surface and the back surface. On the other hand, the organic compound-based antiblocking agent prevents blocking by bleeding out on the surface of the ink layer. Therefore, it is preferable to use a particle-based anti-blocking agent and an organic compound-based anti-blocking agent in combination. In particular, silica that improves the adhesion to the pressure-sensitive adhesive is preferred as the particle-based antiblocking agent. Further, as the organic compound-based anti-blocking agent, PE wax that does not significantly reduce the adhesion with the pressure-sensitive adhesive is particularly preferable.

  The addition amount of the particle size blocking inhibitor is preferably 1 to 10% by mass with respect to the ink solid content. Among these, 2-7 mass% is more preferable. If it is 1% by mass or more, the effect of preventing blocking is suitably exhibited, and if it is 10% by mass or less, the ink film is unlikely to become brittle. On the other hand, the addition amount of the organic blocking inhibitor is preferably 1 to 10% by mass with respect to the ink solid content. Among these, 2-7 mass% is more preferable. If it is 1 mass% or more, the effect of blocking prevention will be acquired suitably, and adhesiveness with an adhesive will become favorable in it being 10 mass% or less. Moreover, you may contain other various additives as needed.

  The ink constituting the light shielding layer preferably contains a curing agent, and as the curing agent, a tolylene diisocyanate curing agent that can easily control the elastic modulus of the ink is most preferable.

  The thickness of the light shielding layer is preferably 1 to 10 μm from the viewpoint of light shielding properties and workability at the time of tape punching.

[Light reflection layer]
In the light-shielding pressure-sensitive adhesive tape of the present invention, the surface opposite to the surface having the pressure-sensitive adhesive layer of the light-shielding layer has light reflectivity, so that a light reflection effect can be obtained and the luminance of the display device can be improved. it can. Such a light reflection layer is not particularly limited, but the reflectance is preferably 60% or more, more preferably 80% or more, and most preferably 90% or more. The higher the reflectivity, the higher the brightness improvement effect. Examples of the reflective layer include a vapor deposition layer of a metal such as silver or aluminum, a white resin layer, a white or silver colorant layer, and the like. Moreover, a commercially available resin film having light reflectivity may be used as it is, or a commercially available thin film having light reflectivity may be laminated on the resin film.

  It is also preferable to provide a partial light absorption layer or light diffusion layer on the reflective surface side in order to obtain effects such as improvement in luminance and reduction in luminance unevenness according to the characteristics of the display device used.

  Examples of the light absorbing layer include colored printing such as black printing and gray printing. Of these, black printing is preferable because of its excellent light absorption.

  Examples of the light diffusing layer include white printing having a diffusing effect and diffusion coating using beads or the like. In the case of a diffusion coating such as beads, the surface is preferably not laminated with an adhesive.

[Light-shielding adhesive tape]
The light-shielding pressure-sensitive adhesive tape of the present invention uses the above-described light-shielding layer, so that the ink and the pressure-sensitive adhesive can be used even under high temperature conditions and cold cycle conditions without using a halogen-containing resin such as a vinyl acetate resin. High adhesion.

  The light-shielding pressure-sensitive adhesive tape of the present invention preferably has a halogen (chlorine / bromine / fluorine / iodine) content of 0.3% by mass or less as a whole of the light-shielding pressure-sensitive adhesive tape, preferably 0.05% by mass or less. More preferred are those which are substantially free of halogen. Here, the halogen content is a detection amount when analyzed by fluorescent X-rays. For example, as a fluorescent X-ray analyzer, “ZSX Primus”, “ZSX Primus II”, etc. manufactured by Rigaku are listed.

  As an embodiment of the light-shielding pressure-sensitive adhesive tape of the present invention, any structure having a light-shielding layer between the resin film and the pressure-sensitive adhesive layer may be used. Specifically, as shown in FIG. 1, an embodiment having a light-shielding layer and an adhesive layer only on one surface of the resin film, or a light-shielding layer and an adhesive on one surface of the resin film as shown in FIG. And a layer having a pressure-sensitive adhesive layer on the other surface. Moreover, embodiment which has a light shielding layer and an adhesive layer on both surfaces of a resin film as shown in FIG. 3 may be sufficient. Moreover, as shown in FIG. 4, the embodiment which provided the adhesive layer on both surfaces of the support body which laminated | stacked the reflection layer and the light shielding layer on the single side | surface of the light-reflective resin film may be sufficient. What is necessary is just to select these aspects suitably by a use application.

  The pressure-sensitive adhesive layer may be a single-layer pressure-sensitive adhesive layer, or may be a multilayer composed of a plurality of pressure-sensitive adhesive layers and sheets such as a double-sided pressure-sensitive adhesive tape.

  For the lamination of the light shielding layer on the resin film, a method of laminating by printing the ink composition can be preferably used. As a printing method, printing and lamination can be performed by a known and common method such as letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, and screen printing. Among them, in the light shielding application, it is preferable to print and laminate on a resin film by a gravure printing method two to four times because pinholes are reduced.

  In addition, it is preferable that the resin film surface which laminates | stacks a light shielding layer performs a well-known and usual easy adhesion process. Of these, easy adhesion treatment selected from corona treatment, plasma treatment, and primer treatment is preferred.

  The pressure-sensitive adhesive layer can be formed on a resin film or a light shielding layer by a method generally used for application of a pressure-sensitive adhesive sheet. Specifically, for example, a composition for forming a pressure-sensitive adhesive layer is directly applied to a resin film or a light shielding layer and dried, or once applied on a separator, dried, and then bonded to the resin film or the light shielding layer. It can be formed by a method or the like.

  The thickness of the light-shielding pressure-sensitive adhesive tape of the present invention is preferably 20 to 100 μm, and more preferably 30 to 75 μm. Especially, it is especially preferable that it is 40-65 micrometers. Those having a thickness in this range can be suitably used for a display device, particularly for an LCD module.

The light-shielding pressure-sensitive adhesive tape of the present invention preferably has a light transmission amount of 1 cd / m ² or less when irradiated with light of 10,000 cd / m ² in order to suppress malfunction due to light incidence. More preferably, it is 0.1 cd / m ² or less. For example, as a light box of 10,000 cd / m ² , for example, Dentsu Sangyo Co., Ltd. flat illuminator HF-SL-A48LCG can be used. As the luminance meter, for example, Eye System 3 eye scale 3, Eye scale 4 and Topcon Techno House BM-5A, BM-7, BM-9, etc. can be used.

  2-15N / 10mm is preferable and, as for the 180 degree | times peeling adhesive force of the light-shielding adhesive tape of this invention, 5-15N / 10mm is more preferable. If it is 2N / 10 mm or less, peeling is likely to occur when the light-shielding pressure-sensitive adhesive tape alone is fixed, and if it exceeds 15 N / 10 mm, the reworkability is significantly reduced.

[LCD module]
The light-shielding pressure-sensitive adhesive tape of the present invention is suitable for various display devices because it has a low halogen content, and preferably does not substantially contain it. Particularly, the light-shielding pressure-sensitive adhesive tape for thin LCD modules which are space-saving. Can be suitably used.

  In addition, the light-shielding pressure-sensitive adhesive tape of the present invention can realize excellent light-shielding properties and adhesiveness, and is therefore suitable for sticking between the LCD panel and the backlight housing of the LCD module having the LCD panel and the backlight housing. It is. Examples of such an LCD module include a sidelight type backlight type LCD module.

  Since the LCD module using the light-shielding adhesive tape of the present invention has a low halogen content, the cause of malfunction or malfunction is reduced, and the reliability is high. An LCD module in which the light-shielding pressure-sensitive adhesive tape of the present invention having a light-reflecting layer is attached so that the light-shielding layer side faces the LCD panel side and the light-reflecting layer side faces the backlight housing can achieve excellent luminance.

  As shown in FIG. 5, the general configuration of the sidelight type backlight system includes a reflector 13, a light guide plate 12, a diffusion sheet 11, and a prism that is used as necessary, in a backlight housing 14. The sheet 10 (increasing the brightness) and the LCD panel 15 are laminated in order, and the light source 11 such as an LED (Light Emitting Diode), a cold cathode tube, etc. having a lamp reflector provided on the side of the light guide plate is arranged. is there. The light-shielding pressure-sensitive adhesive tape of the present invention can be exemplified as a preferred embodiment in which the frame is punched and sandwiched between the LCD panel 15 and the backlight housing 14.

  Since the light-shielding pressure-sensitive adhesive sheet of the present invention can suppress malfunction of peripheral devices and provides a highly reliable product, it is suitably used for display devices of miniaturized electronic devices such as electronic notebooks, mobile phones, and PHS. The LCD module which can be used and contains this light-shielding adhesive sheet can be used suitably for these electronic device uses.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition, the part displayed below is a mass part.

[Black ink production example 1]
Degussa carbon black “4A” 5 parts, Degussa carbon black “Special 250P” 5 parts, Arakawa Chemical polyurethane “KL-564” 14 parts, Eastman cellulose acetate propionate “CAP482” -05 ”, 2 parts of silica“ Silicia 350D ”manufactured by Fuji Silysia Chemical Ltd., 44 parts of methyl ethyl ketone, 23 parts of toluene, and 6.4 parts of ethyl acetate were added, and wet dispersed in a sand mill for about 1 hour. 6 parts of a curing agent “XS-100 Hardener” (tolylene diisocyanate curing agent) manufactured by Dainippon Ink & Chemicals, Inc., and 35 of a diluent “Daireducer V No. 20” manufactured by Dainippon Ink & Chemicals, Inc. A black ink A was prepared by adding a portion. In addition, resin represents solid content ratio.

[Black ink production example 2]
Instead of 6 parts, 8 parts of the curing agent “XS-100 hardener” of Production Example 1 was added to prepare black ink B in the same manner.

[Black ink production example 3]
A black ink C was prepared in the same manner by adding 4 parts of the curing agent “XS-100 Hardener” of Production Example 1 instead of 6 parts.

[Black ink production example 4]
Instead of 6 parts of the curing agent “XS-100 Hardener” in Production Example 1, 4 parts of “CVL Hardener No. 10” (hexamethylene diisocyanate type curing agent) manufactured by Dainippon Ink & Chemicals, Inc. was added, and the same was applied to black. Ink D was prepared.

[Black ink production example 5]
100 parts of “Panacia CVL-SP805 ink” manufactured by Dainippon Ink & Chemicals, Inc., 4 parts of “CVL Hardener No. 10” manufactured by Dainippon Ink & Chemicals, Inc. Black ink E was prepared by adding 35 parts of Direducer V No.20.

[Create evaluation sheet]
On the polyester film having a thickness of 75 μm, the black inks A to E were applied so that the thickness after drying was 40 μm, and after curing for 24 hours under conditions of an environmental temperature of 23 ° C. and a humidity of 50%, The ink films A to E for evaluation were obtained by curing at an environmental temperature of 40 ° C. for 2 days.

  The following items were evaluated for the evaluation ink coatings A to E obtained above. The obtained results are shown in Table 1.

[Measurement of elastic modulus, elongation, breaking strength, breaking elongation]
The ink coating film obtained above is processed into a width of 10 mm and a length of 150 mm, and the chuck is 100 mm using a Tensilon universal tensile tester (Orientec, RTA100) under the conditions of an environmental temperature of 23 ° C. and a humidity of 50%. At that time, the elastic modulus, tensile strength, breaking strength, and breaking elongation were measured when pulled at 300 mm / min.

[Measurement of storage elastic modulus E 'at high temperature]
The ink coating film obtained above was punched out using a dumbbell cutter having a test piece type 5 of JIS K 7127, and the frequency was increased to 3.5 Hz using RSA-2 manufactured by TA Instruments. The storage elastic modulus E ′ was measured under the condition of a speed of 3 ° C./min.

[Production of substrate]
Teraflex FW2 # 13 manufactured by Teijin DuPont Films Co., Ltd. was subjected to corona treatment so that the surface state was 50 dynes or more, and black inks A to E were gravure coated twice so that the dry thickness was 4 μm. The drying was left at room temperature for 2 minutes. Thereafter, the film was cured at 40 ° C. for 2 days to obtain ink coat films A to E.

[Adjustment of adhesive]
(Adjustment of acrylic pressure-sensitive adhesive solution A):
In a reaction vessel equipped with a condenser, stirrer, thermometer, and dropping funnel, 93 parts of n-butyl acrylate, 3.4 parts of vinyl acetate, 3.5 parts of acrylic acid, 0.1 part of β-hydroxy-ethyl acrylate, polymerization As an initiator, 0.2 part of 2,2′-azobisisobutylnitrile is dissolved in 100 parts of ethyl acetate, substituted with nitrogen, polymerized at 80 ° C. for 8 hours, and an acrylic copolymer having a mass average molecular weight of 800,000 ( 1) was obtained. 100 parts of the above acrylic copolymer (1), 10 parts of “Superester A100” manufactured by Arakawa Chemical Co., Ltd., and 10 parts by weight of “Pencel D135” manufactured by Arakawa Chemical Industries are diluted with toluene, and the solid content is 40%. An acrylic pressure-sensitive adhesive composition A was obtained.

[Elemental analysis]
The halogen content was analyzed by the FP method using a wavelength dispersive fluorescent X-ray “ZSX Primus” manufactured by Rigaku.

[Evaluation of light shielding properties of tape by light box]
The light box “Flat Illuminator HF-SL-A48LCG” manufactured by Dentsu Sangyo Co., Ltd. is adjusted to 10000 cd / m ² , and a light-shielding adhesive tape is placed on the light box. ) Measure with an eye system luminance meter “eye scale 3”.

[Adhesive strength]
The adhesive strength was determined by the following procedure in accordance with the JIS-Z0237 (2000) 180-degree peeling adhesive strength test method.
The pressure-sensitive adhesive tapes of Examples and Comparative Examples 20 mm wide lined with a polyester film 25 μm on a stainless steel plate were pressure-applied once with a 2 kg roller under the conditions of an environmental temperature of 23 ° C. and a humidity of 50%, and left for 1 hour. Using a Tensilon universal tensile tester (Orientec, RTA100), the film was pulled at a speed of 300 mm / min under the same temperature and humidity conditions, and then peeled off by 180 degrees to measure the adhesive force.

[Rebound resistance]
As shown in FIG. 12, a 100 μm PET film (Unite Emblet SA # 100) and a 2 mm thick polycarbonate (PC) plate are attached with a 2 mm wide tape. Thereafter, pressurization is performed under the condition of one reciprocation of the 2 kg roller, and the floating peeling after observing at 85 ° C. for 72 hours is observed.
○: Peeling of the ink layer and the pressure-sensitive adhesive layer does not occur.
X: Peeling of the ink layer and the pressure-sensitive adhesive layer occurs.

[Pinhole]
A light box “Flat Illuminator HF-SL-A48LCG” manufactured by Dentsu Sangyo Co., Ltd. was adjusted to 10000 cd / m ² , and a light-shielding adhesive tape was placed thereon, and 0.1 mm × 0.00 mm in A4 size. Pinholes with a size of 1 mm or more were counted.
◎: None ○: 1 to 10 ×: 11 or more

Example 1
[Production of adhesive tape]
On the polyester film having a thickness of 75 μm, which was mixed with 1.2 parts of “Coronate L-45” (isocyanate-based cross-linking agent) manufactured by Nippon Polyurethane Industry Co., Ltd. in the acrylic pressure-sensitive adhesive composition A, and after sufficiently stirring. The film was coated so that the thickness after drying was 20 μm, and dried at 85 ° C. for 2 minutes to obtain a pressure-sensitive adhesive layer. This was transferred to both sides of the ink coat film (A), laminated with a 80 ° C. hot roll at a pressure of 4 kgf / cm, and further cured at 40 ° C. for 2 days to obtain a double-sided adhesive tape. Permeation amount when irradiated with light of the resulting tape 10000 cd / ^{m 2} is 0.5 cd / ^{m 2,} also observed pinholes 0.1 mm × 0.1 mm or more in size in A4 size It was. Furthermore, the adhesive force was 5 N / 10 mm.

(Example 2)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (B) was used instead of the ink coat film (A). Permeation amount when irradiated with light of the resulting tape 10000 cd / ^{m 2} is 0.5 cd / ^{m 2,} also observed pinholes 0.1 mm × 0.1 mm or more in size in A4 size It was. Furthermore, the adhesive force was 5 N / 10 mm.

(Comparative Example 1)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (C) was used instead of the ink coat film (A). Permeation amount when irradiated with light of the resulting tape 10000 cd / ^{m 2} is 0.5 cd / ^{m 2,} also observed pinholes 0.1 mm × 0.1 mm or more in size in A4 size It was. Furthermore, the adhesive force was 5 N / 10 mm.

(Comparative Example 2)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (D) was used instead of the ink coat film (A). Permeation amount when irradiated with light of the resulting tape 10000 cd / ^{m 2} is 0.5 cd / ^{m 2,} also observed pinholes 0.1 mm × 0.1 mm or more in size in A4 size It was. Furthermore, the adhesive force was 5 N / 10 mm.

(Reference Example 1)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (E) was used instead of the ink coat film (A). Permeation amount when irradiated with light of the resulting tape 10000 cd / ^{m 2} is 0.5 cd / ^{m 2,} also observed pinholes 0.1 mm × 0.1 mm or more in size in A4 size It was. Furthermore, the adhesive force was 5 N / 10 mm.

  About the double-sided adhesive tape obtained by the said Example, the comparative example, and the reference example, the following items were evaluated. The obtained results are shown in Table 2.

  As is clear from the results shown in Table 2, the adhesive tapes of Examples 1 and 2 have good adhesiveness and light shielding properties with respect to an adhesive even if they do not contain a halogen content, and have few pinholes.

  On the other hand, the pressure-sensitive adhesive tapes of Comparative Examples 1 and 2 do not contain halogen and have good light-shielding properties, but are inferior in adhesion to the pressure-sensitive adhesive at higher temperatures than those of the examples, and peeling occurs.

  Further, the pressure-sensitive adhesive tape of Reference Example 1 has good adhesiveness and light shielding properties with respect to a pressure-sensitive adhesive, has few pinholes, but contains halogen.

It is a notional schematic sectional drawing which shows an example of the adhesive tape of this invention which provided the adhesive layer 4 in the light shielding layer 2 side of the support body 3 which laminated | stacked the resin film 1 and the light shielding layer 2. FIG. It is a conceptual schematic sectional drawing which shows an example of the adhesive tape of this invention which provided the adhesive layer 4 on both surfaces of the support body 3 which laminated | stacked the resin film 1 and the light shielding layer 2. FIG. It is a conceptual schematic sectional drawing which shows an example of the adhesive tape of this invention which provided the adhesive layer 4 on both surfaces of the support body 3 which laminated | stacked the light shielding layer 2 on both surfaces of the resin film 1. FIG. It is a conceptual schematic sectional drawing which shows an example of the adhesive tape of this invention which provided the adhesive layer 4 on both surfaces of the support body 3 which laminated | stacked the reflection layer 6 and the light shielding layer 2 on the single side | surface of the light-reflective resin film 5. FIG. 2 is a conceptual schematic cross-sectional view of an LCD module in which each component such as an LCD panel 15 is fixed to a backlight housing 14 using an adhesive tape 8. FIG.

Explanation of symbols

1: resin film 2: light shielding layer 3: support 4: adhesive layer 5: light reflective resin film 6: light reflective layer 7: driver 8: adhesive tape 9: prism sheet 10: diffusion sheet 11: light source 12: light guide plate 13: Reflector 14: Backlight housing 15: LCD panel

Claims (11)

A light-shielding pressure-sensitive adhesive tape comprising at least a resin film, a light-shielding layer and a pressure-sensitive adhesive layer, and having a light-shielding layer between the resin film and the pressure-sensitive adhesive layer, wherein the halogen content in the light-shielding layer is 0.3% by mass The light-shielding layer is a layer made of colored ink. The elastic modulus of the ink in a sheet form with a thickness of 40 μm is 0.3 to 5 GPa, and the tensile strength is 10 MPa in the tensile direction. A light-shielding pressure-sensitive adhesive tape having an elongation of 0.5 to 10%. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the ink has a tensile strength at break of 20 to 50 MPa and a tensile elongation at break of 10 to 60% in a sheet form having a thickness of 40 μm. The light-shielding pressure-sensitive adhesive tape according to claim 1 or 2, wherein the ink has a sheet shape with a thickness of 40 µm and a storage elastic modulus (E ') at 85 ° C of 0.1 to 1 GPa. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the ink contains a polyurethane-based resin as a binder resin. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the ink contains a tolylene diisocyanate curing agent. The loss tangent at 85 ° C of the dynamic viscoelastic spectrum at a frequency of 1 Hz of the pressure-sensitive adhesive layer is 0.35 to 0.7, and the storage elastic modulus at 85 ° C is 15000 to 25000 Pa. The light-shielding pressure-sensitive adhesive tape according to Crab. The light-shielding pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer contains an acrylic copolymer containing 2 to 10% by mass of an acrylic acid unit. The light-shielding pressure-sensitive adhesive tape according to claim 1 the amount of transmitted light when irradiated with light of 10000 cd / ^{m 2} is 1 cd / ^{m 2} or less. The light-shielding pressure-sensitive adhesive tape according to claim 1, further comprising a light reflecting layer between the resin film and the light-shielding layer or between the light-shielding layer and the pressure-sensitive adhesive layer. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the resin film is a light-reflective resin film. An LCD module having an LCD panel and a backlight housing, wherein the LCD panel and the backlight housing are adhered with the light-shielding adhesive tape according to claim 1. LCD module characterized by

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